Help with an unknown device trying to connect to my mac mini

I am receiving near-constant Bluetooth connection requests from a device called "iPhone" to my Mac mini . This pop-up window appears every other minute with a different connection code each time. I have 3 options in the pop-up window: Connect, Cancel, or a checkbox for "Ignore this device." I have clicked on each of them multiple times but to no avail. The pop-up window returns soon after. I have tried the following:

• Turning on my firewall to refuse all incoming connections
• Checking Bluetooth preferences to try to find a way to refuse or block that connection

Can you help?